The United States and Japan will step up their defence cooperation to deal with the threat from nuclear-armed North Korea as tensions in East Asia remain high, officials from the two allies said on Thursday.

We could have done more: school teacher

In hindsight, it was a recipe for disaster: a steady stream of boys, an office you couldn't see into, a lighting system to warn people off and a "stiff upper lip" culture that discouraged student complaints.

Yet it was one that let former Brisbane Grammar School counsellor Kevin John Lynch abuse "dozens and dozens and dozens" of children throughout his employment, an inquiry has heard.

According to this witness, Lynch's predatory tactics were common knowledge among students, and counselling sessions were colloquially termed "wanking with Skippy" - a play on the polio-stricken counsellor's nickname.

Mr Cochrane agreed the set-up of Lynch's office, combined with a tough school atmosphere, aided the abuse of students.

But he said he never heard any rumours about the depraved treatment being doled out behind the counsellor's locked doors.

That sentiment was echoed by former deputy headmaster David Coote, who had been Lynch's closest friend at the school.

He said there had been no oversight of the counsellor because he had to maintain client confidentiality with students as part of his role.

The inquiry heard that Mr Coote gave a eulogy at Lynch's funeral praising him as "fully human" and the best counsellor he'd known in 40 years of professional experience.

He used these words despite being told by a St Paul's staff member moments earlier that Lynch had been under investigation for sexually assaulting a student.

Asked if he felt the need to apologise for Lynch's prolific abuse of students, Mr Coote replied: "What good is an apology? It happened.

"If everybody would feel better if I apologise, then I apologise," he eventually offered.